One-use hand-cleaning tablets



United States Patent 3,487,021 ONE-USE HAND-CLEANING TABLETS Abraham Taub, New York, N.Y., assiguor to Jacob M. Katz, New York, N.Y. No Drawing. Filed Aug. 11, 1966, Ser. No. 571,723 Int. Cl. Clld 3/22, 1/28 US. Cl. 252-161 1 Claim ABSTRACT OF THE DISCLOSURE The tablet, which disintegrates in less than one minute, comprises a detergent which is a sodium alkyl linear sulfate, in which the alkyl substituent is a straight chain of 12-16 carbon atoms, a carrier which is lactose produced by a spray-dry process yielding a free flowing granule of 60-100 mesh, and a disintegrant which is hydrophobic starch ester.

The present invention relates to a one-use detergent tablet particularly suitable for cleaning hands being wetted in water.

The principal object of this invention is to provide a novel and improved one-use dry synthetic detergent tablet having the following attributes:

(a) The tablet shall be of such composition and structure that it will quickly disintegrate upon getting wet, but the release of its detergent content will be controlled so the individual grains thereof will completely dissolve and thus avoid their formation into a tenacious gelatinous mass.

(b) The detergent content of the tablet shall have high and rapid foaming capacity and be bio-degradable.

(c) The ingredients comprising the tablet shall be commercially available products requiring no preliminary treatment such as wet granulation or dry slugging, and in physical combination shall be directly compressible by usual tableting means without sticking or capping in the mold, or in any way offering or creating other opposition to easy and entire ejection from the mold in tablet form.

((1) The tablet shall remain non-hygroscopic, and the tablets in contact with each other, shall remain free of tackiness or softening in storage so they may be housed in dispensing devices. Though exposed to high humidity environments, said tablets shall remain hard and free from flaking.

(e) The tablet shall be mild to the hands, economical to manufacture and eflicient in use.

Other objects and advantages will become apparent as this disclosure proceeds.

For the practice of this invention, the tablet is comprised essentially of three water-soluble ingredients, namely a synthetic detergent, a diluent serving as a carrier, and a disintegrant. The carrier and disintegrant are chosen to accomplish certain physical behaviors, which will now be explained.

It is to be noted that individual grains of dry detergent when wetted with a little water, swell to form gel-like beads. These tend to bond together if they are near each other and form a tenacious soap-like gel or cake. By keeping the detergent particles far enough apart, which is accomplished by the carrier here chosen, the continuous action of the water used in washing the hands, dissolves the little gel beads and they remain in solution, too dilute to produce a soap-like gel. If a carrier is used which dissolves too rapidly, the undissolved detergent particles are brought close together and bond to each other to form a large tenacious gel. With a slowly dissolving carrier as herein employed, the water dissolves the detergent particles before or simultaneously with the dissolving of the carrier, and so, the detergent, now in solution, can no longer gel at this high dilution. All of the original solid lce detergent particles being now in solution, they exert their full foaming and cleansing action.

Further, the ingredients herein chosen, will form into a tablet which will have ample strength and hardness so it will not break, shed or become tacky before put to use, and which will readily disintegrate when wetted and rubbed in hand.

For the ingredients of the tablet of this invention, I use a synthetic detergent which is of a first group known a sodium alkyl linear sulfates in which the alkyl substituent is a straight chain of 12 to 16 atoms, or of a second group known as sodium linear alkyl aryl sulfonates, in which the alkyl substituent is a straight chain of 12 to 16 carbon atoms. An example from the first group is sodium lauryl sulfate, and an example from the second group is sodium lauryl benzene sulfonate. For the carrier, I use lactose (milk sugar) which has been produced by a spray dry process, yielding a granule which is free flowing and about 60 to 100 mesh. It is to be noted that powdered lactose or crystalline lactose will not do, because they would dissolve out too fast and caking would result. The detergent would agglomerate.

For the disintegrant, I use a starch chemically treated to form solid esters which are hydrophobic, id est, water repellant. An example in commerce, is a product marketed by National Starch and Chemical Corp., under the name of Dry Flo, whose describe it as of value as a general lubricant, dusting powder for rubber and plastic sheeting,

and as a processing aid. I have discovered that it will serve for my purpose as an effective and efiicient disintegrant.

I will now set forth the composition of actual tablets made and tested by me, which in use, release a white foamy slurry on the hands when wetted and rubbed. The tablet rapidly diminishes in size and ends up as a foamy whitish liquid covering the hands when rubbed. In the following examples, parts indicated are by weight.

EXAMPLE 1 Parts Sodium lauryl sulfate, dry 5 Lactose, spray-dried, of 60-100 mesh Hydrophobic corn starch ester 20 The powders are mixed by tumbling or twin-blending, and compressed into /2 inch diameter flat tablets having a weight of 0.8 gram and a Strong-Cobb hardness of 3.

GENERAL FORMULA Other examples of the ingredients herein named, made and tested, show the general formula for tablets of this invention to be:

Detergent From 1 to 20 percent Disintegrant From 2 to 30 percent Carrier Balance to make wherein the ratio of the disintegrant to the detergent and is from about 2 to 5, and the tablet hardness measured by a Strong-Cobb hardness tester, is about 3 to 10 kilograms.

In the mode of operation of these tablets, water enters the minute pores of the compressed tablet and selectively wets the detergent first because of its low surface tension. The water then begins to dissolve the lactose carrier, which is slowly soluble. It then enters the starch granules. These begin to swell and cause the entire tablet to increase in volume and begin to disintegrate. The process is facilitated by the rubbing action of the hands on the now porous tablet. If instead of the lactose used, common water-soluble carriers like salt or sucrose were used, they would be washed away quickly and leave a tenacious detergent gel in the hands, which like a small bar of soap, takes a long time to dissolve. In the presence of the spray-dried granular lactose, the

3 detergent particles have time to dissolve completely while separated from each other by the more slowly dissolving lactose.

Tablets made as above, were exposed for one month in an environment of 80% relative humidity at 20-30 degrees Centigrade. They showed no softening or swelling and had no tackiness. Tablets made as taught herein are biodegradable, disintegrate in less than one minute, and are suitable for loading at random into hoppers of dispensing devices, and have all the other mentioned beneficial attributes.

Of importance to note is that the tablet taught herein is a structure in which the ingredients make a physically spaced combination which permits water interaction on the components thereof, at a rate which prevents gelling of the powdered detergent particles. The tablets in contact, will not stick to each other even in high humidity environments to which they are subjected for instance in public wash rooms, and they will not break in transit 20 or storage.

The term detergent as used herein shall be deemed not to include ordinary soaps.

I claim as my invention:

1. A dry one-use hand-cleaning tablet consisting essentially of sodium lauryl sulfate of 5 parts by weight, 75 parts by weight of a carrier consisting of lactose produced by a spray-dry process yielding a granule which is free flowing in a 60-100 mesh, and 20 parts by weight of a disintegrant consisting of hydrophobic starch ester.

References Cited UNITED STATES PATENTS 2,191,678 4/1938 Nitardy et al. 167-82 3,091,574 5/1963 061cm et a1. 167-82 FOREIGN PATENTS 626,252 8/1961 Canada.

LEON D. ROSDOL, Primary Examiner P. E. WILLIS, Assistant Examiner 

